Explosive environment termination of wellhead cables

ABSTRACT

Technologies are generally described for apparatus, systems, and methods to reduce cost and simplify couplings for wellhead equipment and related cable assemblies. The wellhead equipment is placed on a well that is bored into the ground. The wellhead cable may employ a splice assembly that includes a downhole cable, a surface cable, and a conduit. The surface cable is spliced with the downhole cable below a wellhead hanger. The conduit may be configured to contain the surface cable and terminate in the explosion-proof conduit box located at the surface. An inner space of the conduit may be sealed below the wellhead hanger. The conduit may be break-free, or contiguous, between the wellhead hanger and the explosion-proof box.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/031,632 filed on May 29, 2020. The disclosures of the above application are hereby incorporated by reference for all purposes.

BACKGROUND

Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted as prior art by inclusion in this section.

Oil and similar underground extraction systems include electrical submersible pumps and other equipment that operate in a drill hole submerged in a fluid (e.g., oil, water, oil-water mixture, etc.). Such equipment, in addition to being submerged, are typically subject to high pressures and/or high temperatures. Power to the submersible equipment is provided through downhole and surface cables that are spliced above the wellhead or in the vicinity of the wellhead. Various methods of fortifying the cables at their splicing location may include use of epoxy, steel tubing, etc., but add complexity and/or cost to the system.

SUMMARY

The present disclosure generally describes a method, system, and apparatus to reduce cost and simplify assembly of wellhead equipment and related cable assemblies. Example wellhead equipment contemplated herein may include an electric submersible pump, related cable assembly, and tubing that encapsulates surface-side cables.

The gases (and oil) in wells create an environment that may be susceptible to fire and explosions. Thus, wellhead equipment is typically designed and implemented according to explosion safety standards. Costly explosion-proof conduits and connection components are typically used in wellheads. According to some example embodiments of the presently disclosed technologies, tubing from a downhole penetrator may be extended up into an explosion-proof enclosure. The tubing, and the electrical cable contained within, are not separated until within the enclosure removing a need for an additional mechanical connection, explosion-proof conduit, explosion-proof unions, high amperage restricted “hot spots”, and any additional work required to terminate the tubing and cable for this connection at the surface.

In some examples of the presently disclosed technologies, an apparatus is described for a wellhead cable splice assembly. Example wellhead cable splice assemblies may include a downhole cable, a surface cable, and a conduit. The surface cable is spliced with the downhole cable below a wellhead hanger. The conduit may be configured to contain the surface cable and terminate in the explosion-proof conduit box located at the surface. An inner space of the conduit may be sealed below the wellhead hanger. The conduit may be break-free, or contiguous, between the wellhead hanger and the explosion-proof box.

In various other examples of the presently disclosed technologies, methods to form a wellhead cable splice assembly are described. Examples methods may include, electrically coupling a downhole cable and a surface cable through a crimped or crimp-free contact, providing the surface cable through a conduit, wherein a downhole termination of the conduit is coupled to a downhole connector, providing the conduit through a wellhead hanger to an explosion-proof conduit box on the surface, securing the conduit through a fitting to a top surface of the wellhead hanger, and securing the conduit through another fitting to the explosion-proof conduit box.

In some examples of the presently disclosed technologies, a system is described for a wellhead cable to electrically couple surface equipment to in-well equipment that is located below a surface of a wellhead hanger of a wellhead. Example wellhead cable systems may include an explosion-proof conduit box, a conduit, a downhole cable, and a surface cable. The explosion-proof conduit box may be located above the surface. The conduit may include first and second ends, where a first end of the conduit may be sealed at the explosion-proof box, a second end of the conduit may be sealed at the wellhead, and the conduit may contiguously extend from the explosion-proof conduit box to the wellhead. The downhole cable may include a first end and a second end, where the first end of the downhole cable may be configured to electrically couple to the in-well equipment below the wellhead. The surface cable may include a first end and a second end. The first end of the surface cable may be configured to couple to surface equipment within the explosion-proof conduit box. The second end of the surface cable may be spliced to the second end of the downhole cable either within the wellhead hanger or in the wellhead. The surface cable may contiguously extend from the exposition-proof conduit box to the wellhead hanger or the wellhead within the conduit.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of this disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings, in which:

FIG. 1 illustrates a cross-sectional view of a well and wellhead with example equipment;

FIG. 2 illustrates a side view of a conduit and wellhead, where surface cables are provided directly into the explosion-proof conduit box through tubings;

FIGS. 3A and 3B illustrate a model of an explosion-proof conduit box receiving cables through tubings directly from the wellhead; and

FIG. 4 illustrates the single fitting per cable configuration of an example system;

all arranged in accordance with at least some embodiments described herein.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. The aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

This disclosure is generally drawn, inter alia, to methods, apparatus, systems and/or devices that may be employed to splice an electric submersible pump cable and a tubing encapsulated surface-side cable.

FIG. 1 illustrates a cross-sectional view of a well and wellhead with example equipment, arranged in accordance with at least some embodiments described herein.

As shown in FIG. 1, a wellhead 104 may be placed on a well 118, which is bored into ground 102. In-well equipment, such as downhole pump 108 and similar ones, may be submerged in fluid 106 (gas or liquid) and have one or more fluidic couplings 114 (e.g., via a fluid coupler such as a pipe, tube, channel or conduit) to surface mechanical equipment 110 such as pumps, filters, compressors, etc. In-well equipment may also have one or more electrical couplings 116 (e.g., an electrical coupler or conductor such as a wire, cord, line, or cable) to surface electrical devices or systems 112 such as power supplies, controllers, amplifiers, switches, etc.

In some examples, a tube from a downhole penetrator may extend up into an explosion-proof enclosure (for example, as part of the surface electrical devices or systems 112 or prior to those). The tube, which includes an electrical cable contained within, are not separated until located within the explosion-proof enclosure. This may reduce or eliminate a need for any additional mechanical connection, explosion-proof conduit, explosion-proof unions, high amperage restrictions, and any additional work that may be required to terminate the tube and electrical cable for a connection at the surface. A uni-directional pressure block may be used in a cable splice for each individual conductor of the electrical cable. The cable splices may be inserted directly into wellhead hanger bores or may be assembled into housings that seal directly (via O-rings or pipe threads) to existing features in a wellhead. The cable splices may be of any variety such as a tape splice, a mechanical splice, etc. In some examples, a tape splice may be compatible with a wide range of downhole cable sizes.

FIG. 2 illustrates a side view of a conduit and wellhead, where surface cables are provided directly into the explosion-proof conduit box through tubings, arranged in accordance with at least some embodiments described herein.

Diagram 200 includes a conduit box 202 receiving conduits 204, 206 (two out of three conduits in a tri-bore configuration shown) and retaining nuts 208, which secure the conduits to the wellhead.

As shown in diagram 200, a partial length of a surface cable 206 and a complete surface cable in conduit 204, which are secured into the conduit box 202, where the cables may be further spliced for further surface connections, connected to fuses, terminals, and other devices. In some example implementations, the surface cables may each be comprised of #4 AWG electrical wires that are housed in a ⅜″ diameter metal tube or conduit. By extending the conduits 204, 206 (tubings) from the downhole penetrator into an explosion-proof enclosure, and not separating the tubing until within the enclosure, additional explosion-proof measures between the enclosure and the submerged pump can be eliminated as unnecessary. Some of the example benefits that may be realized by this implementation include a reduced cost of implementation, a reduced cost of replacement parts, and a simplified overall assembly.

Each surface cable and corresponding downhole cable may be electrically coupled to one another through a splice using either a conductive crimp or a crimp-free contact. O-ring(s) and/or a rubber bootseal(s) may be used to prevent leakage of fluids or gases inside the tubings. For example, multiple O-rings may provide sealing at various locations (e.g., at or near couplings, between insulator and conduit, etc.).

FIGS. 3A and 3B illustrate a model of an explosion-proof conduit box, shown in FIG. 2, receiving cables through tubings directly from the wellhead; arranged in accordance with at least some embodiments described herein.

Compared to conventional implementations, a system according to embodiments utilizes simple and relatively inexpensive tubings 302 and fittings at the wellhead “B” and explosion-proof conduit box “A”. Thus, there are no explosion-proof connections or hot spot breaks in the cable on the surface. Furthermore, height requirement to make the connection is also reduced compared to conventional systems. As the cable is fed through the tubings 302 from downhole to the surface, ensuring sealing of the tubings downhole makes it unnecessary to have explosion-proof connections above the surface. Fittings 304, 306 for each conduit to secure the conduits to the wellhead and to the explosion-proof conduit box are sufficient.

FIG. 4 illustrates the single fitting per cable configuration of a system, arranged according to at least some embodiments described herein.

Diagram 400 shows a tri-bore cable connection according to embodiments, where the cables are provided inside conduits (or tubings) through the wellhead into an explosion-proof conduit box without a break. Thus, complex connections are not required, and the overall design is simplified. The complex connections found in conventional systems are replaced with simple fittings 402 that secure the tubings to the wellhead (and the conduit box). Some of the benefits achieved include lower cost, easier assembly, easier repair and servicing, and lower cost and simplified replacement parts.

A cable splice employing a mechanical or taped pressure block may allow insulated electrical conductors to pass through a wellhead while preventing fluids (gas or liquid) under high pressure from escaping into the outside environment (and into the cable assembly).

The termination of tubing encapsulated cable into a flame-proof or explosion-proof enclosure may allow reduction of parts and complexity wellhead systems while preserving safety. Consequently, installation and maintenance efforts and costs may also be reduced. In some examples, metal-to-metal tubing seals may be used for explosion-proof or flame-proof fitting. The metal-to-metal seal fitting has fewer parts compared to conventional fittings, is less complex, and does not require epoxy seal. The metal-to-metal seal fitting may be used to prevent explosions from propagating along the path outside the tubing encapsulated cable.

Some example implementations may include a downhole connector that can withstand explosions from surface equipment. The downhole connector can withstand pressure from well conditions as well as pressure seen in case of explosion within the enclosure on the surface. In case the explosive gases communicate through the inside space of the tubing, the downhole connector (splice tube in this case) may stop the propagation of the explosion into the well bore. This secondary function of bi-directional pressure block may remove a need for an intermediate epoxy explosion block.

The fittings and the downhole connector may work as a system. The fittings stop propagation on the path outside of the tubing encapsulated cable and the downhole connector blocks the path along the inside diameter of the tubing encapsulated cable. The two allow for the completed system to be viable.

The fittings may have standard threads, for example ½ inch national pipe thread (NPT), or custom. In an example implementation, the surface cables may be #4 AWG Polyetheretherketone (PEEK) insulated pigtail cable in ⅜″ metal tubing. The downhole cable may have a lead jacket. Of course, other types of insulators may be used for the surface and downhole cables.

The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, are possible from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. Such depicted architectures are merely examples, and in fact, many other architectures may be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermediate components. Likewise, any two components so associated may also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality, and any two components capable of being so associated may also be viewed as being “operably couplable”, to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically connectable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

In general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation, no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations).

Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general, such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

For any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments are possible. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. 

What is claimed is:
 1. A wellhead cable splice assembly comprising: a downhole cable; a surface cable spliced with the downhole cable below a wellhead hanger; and a conduit configured to contain the surface cable and to terminate in an explosion-proof conduit box on the surface, wherein an inner space of the conduit is sealed below the wellhead hanger, and the conduit is break-free between the wellhead hanger and the explosion-proof conduit box.
 2. The wellhead cable splice assembly of claim 1, further comprising: a fitting to secure the conduit to a top surface of the wellhead; and another fitting to secure the conduit to the explosion-proof conduit box.
 3. The wellhead cable splice assembly of claim 2, wherein the fitting and the other fitting are threaded fittings.
 4. The wellhead cable splice assembly of claim 1, wherein the inner space of the conduit is sealed below the wellhead hanger through one or more O-rings.
 5. The wellhead cable splice assembly of claim 1, wherein the inner space of the conduit is sealed below the wellhead hanger through a sealing tape wound around a top portion of the downhole cable.
 6. The wellhead cable splice assembly of claim 1, wherein an outer diameter of the conduit is selectable to fit into an existing wellhead hanger.
 7. The wellhead cable splice assembly of claim 1, wherein the surface cable is #4 American Wire Gauge (AWG) cable covered by Polyetheretherketone (PEEK) insulator.
 8. The wellhead cable splice assembly of claim 1, wherein the surface cable and the downhole cable are spliced through a crimped or crimp-free connection.
 9. The wellhead cable splice assembly of claim 1, further comprising a downhole connector configured to withstand one or more of downhole pressures and an explosion within the explosion-proof conduit box.
 10. A method to form a wellhead cable splice assembly, the method comprising: electrically coupling of a downhole cable and a surface cable through a crimped or crimp-free contact; providing the surface cable through a conduit, wherein a downhole termination of the conduit is coupled to a downhole connector; providing the conduit through a wellhead hanger to an explosion-proof conduit box on the surface; securing the conduit through a fitting to a top surface of the wellhead hanger; and securing the conduit through another fitting to the explosion-proof conduit box.
 11. The method of claim 10, further comprising: sealing an inside space of the conduit through one or more O-rings below the wellhead hanger.
 12. The method of claim 10, further comprising: sealing an inside space of the conduit through a sealing tape wound around a top portion of the downhole cable below the wellhead hanger.
 13. A wellhead cable system to electrically couple surface equipment to in-well equipment that is located below a surface of a wellhead hanger of a wellhead, the wellhead cable system comprising: an explosion-proof conduit box that located above the surface; a conduit that includes first and second ends, wherein a first end of the conduit is sealed at the explosion-proof box, a second end of the conduit is sealed at the wellhead, and the conduit contiguously extends from the explosion-proof conduit box to the wellhead; a downhole cable that includes a first end and a second end, wherein the first end of the downhole cable is configured to electrically couple to the in-well equipment below the wellhead; a surface cable that includes a first end and a second end, wherein the first end of the surface cable is configured to couple to surface equipment within the explosion-proof conduit box, the second end of the surface cable is spliced to the second end of the downhole cable either within the wellhead hanger or in the wellhead, and surface cable contiguously extends from the exposition-proof conduit box to the wellhead hanger or the wellhead within the conduit.
 14. The wellhead cable system of claim 13, wherein the second end of the conduit is secured and sealed within bores of the wellhead hanger.
 15. The wellhead cable system of claim 13, wherein the send end of the conduit is secured and sealed within existing features of the wellhead.
 16. The wellhead cable system of claim 13, further comprising a uni-directional pressure block that is inserted within the bores of the wellhead hanger and configured to splice each individual conductor of the surface cable to each corresponding conductor of the downhole cable.
 17. The wellhead cable system of claim 13, further comprising a uni-directional pressure block that is inserted within existing features of the wellhead hanger and configured to splice each individual conductor of the surface cable to each corresponding conductor of the downhole cable.
 18. The wellhead cable system of claim 1, wherein the surface cable and the downhole cable are spliced through either a crimped or crimp-free connection.
 19. The wellhead cable splice assembly of claim 1, wherein the in-well equipment corresponds to a submersible downhole pump.
 20. The wellhead cable splice assembly of claim 1, wherein the surface equipment corresponds to one or more of a pump, a compressor, or a filter. 